Concentrations Of Adenine Research Articles

Selective voltammetric and flow-injection determination of guanine and adenine on a glassy carbon electrode modified by a ruthenium hexachloroplatinate film

An inorganic film of ruthenium hexachloroplatinate (RuPtCl6), deposited on the surface of a glassy carbon electrode, exhibits electrocatalytic activity in the oxidation of purine bases, such as adenine and guanine. Appropriate working conditions are found for fabricating a polymer film on the surface of glassy carbon and for recording the maximum electrocatalytic effect for the modified electrode. A method is developed for the selective voltammetric determination of guanine and adenine in their simultaneous presence on an electrode modified by a RuPtCl6 film. A procedure is proposed for the amperometric detection of purine bases with this modified electrode under the conditions of flow-injection analysis. The dependence of the analytical signal on the concentration of guanine and adenine is linear up to 5 × 10−6 and 5 × 10−7 M in the stationary mode and to 5 × 10−7 and 5 × 10−8 M under flow conditions, respectively. The proposed method was tested in the analysis of calf thymus DNA for the concentrations of guanine and adenine.

Photochemical method for decoration of silver nanoparticles on filter paper substrate for SERS application

A facile photoreduction strategy to attach silver nanoparticles on filter paper (AgNPs@FP) to form surface‐enhanced Raman scattering (SERS) substrate array was proposed and examined. As prepared, SERS substrate array was applied to detect low concentration of adenine and other nucleobases in aqueous solutions. In addition, the formed SERS substrate array allows mass analysis of aqueous samples with a requirement of only 10 μL in sample volume. To optimize and understand the parameters in preparations, factors such as the concentrations of citrate and silver nitrate, photoreduction time, and concentration of sodium hydroxide were varied and examined. Para‐nitrothiophenol was used as a Raman probe molecule and scanning electron microscope (SEM) images of the substrates were used to explore the influences of experimental factors in the preparation of SERS array. Results indicated that silver ions could be effectively reduced and deposited in/on filter paper with the presence of citrate. The formed AgNPs@FP exhibits a three‐dimensional structure as the particles formed on and beneath the surface of the cellulosic fibers could be observed. Deposition of analyte on restricted substrate array rendered reproducible results and the spot‐to‐spot SERS intensity varied within 8%. At optimal conditions, the substrate enhancement factor approached 107. We demonstrated that the filter paper‐based SERS substrates can be used as a suitable tool for biological analysis, and a limit of detection better than 160 nM was obtained in detection of adenine molecules in aqueous solutions with a linear range up to 20 μM. Copyright © 2014 John Wiley & Sons, Ltd.

Metabolic and bioprocess engineering of the yeastCandida famatafor FAD production

Flavins in the form of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) play an important role in metabolism as cofactors for oxidoreductases and other enzymes. Flavin nucleotides have applications in the food industry and medicine; FAD supplements have been efficiently used for treatment of some inheritable diseases. FAD is produced biotechnologically; however, this compound is much more expensive than riboflavin. Flavinogenic yeast Candida famata synthesizes FAD from FMN and ATP in the reaction catalyzed by FAD synthetase, a product of the FAD1 gene. Expression of FAD1 from the strong constitutive promoter TEF1 resulted in 7- to 15-fold increase in FAD synthetase activity, FAD overproduction, and secretion to the culture medium. The effectiveness of FAD production under different growth conditions by one of these recombinant strains, C. famata T-FD-FM 27, was evaluated. First, the two-level Plackett-Burman design was performed to screen medium components that significantly influence FAD production. Second, central composite design was adopted to investigate the optimum value of the selected factors for achieving maximum FAD yield. FAD production varied most significantly in response to concentrations of adenine, KH2PO4, glycine, and (NH4)2SO4. Implementation of these optimization strategies resulted in 65-fold increase in FAD production when compared to the non-optimized control conditions. Recombinant strain that has been cultivated for 40 h under optimized conditions achieved a FAD accumulation of 451 mg/l. So, for the first time yeast strains overproducing FAD were obtained, and the growth media composition for maximum production of this nucleotide was designed.

Enhanced production of withaferin-A in shoot cultures of Withania somnifera (L) Dunal

Withania somnifera (L) Dunal, commonly known as ashwagandha or Indian ginseng, is the source of large number of pharmacologically active withanolides. Withaferin-A (WS-3), a major withanolide of W. somnifera, has been proven to be an effective anti-cancer molecule. In this study, a liquid culture system for shoot proliferation, biomass accumulation and withaferin-A production of an elite accession (AGB002) of W. somnifera was investigated. The nodal explants cultured on Murashige and Skoog (MS) semi-solid medium supplemented with various concentrations of 6-benzyl adenine (BA) and Kinetin (Kn) elicited varied responses. The highest number of regenerated shoots per ex-plant (35 ± 3.25) and the maximum average shoot length (5.0 ± 0.25 cm) were recorded on MS medium supplemented with BA (5.0 μM). The shoots were further proliferated in half and full strength MS liquid medium supplemented with the same concentration BA. It was interesting to note that shoots cultured on MS half strength liquid medium fortified with 4 gL-1 FW (fresh weight) shoot inoculum mass derived from 5 week old nodal explants of W. somnifera showed highest accumulation of biomass and withaferin A content in 5 weeks. Withaferin A was produced in relatively high amounts (1.30 % and 1.10 % DW) in shoots cultured in half and full strength MS liquid media respectively as compared to natural field grown plants (0.85 % DW). A considerable amount of the withaferin A was also excreted in the culture medium. Successful proliferation of shoots in liquid medium and the synthesis of withaferin A in vitro opens new avenues for bioreactor scale-up and the large-scale production of the compound.

Electrochemical Biosensor consisted of conducting polymer layer on gold nanodots patterned Indium Tin Oxide electrode for rapid and simultaneous determination of purine bases

The present work focused on the development of new simple method for fabrication of conducting poly(4–aminothiophenol) nanostructures layered on gold nanodots patterned indium tin oxide (ITO) electrode based on the self assembly of the monomer. This was followed by electrochemical polymerization of 4–aminothiophenol molecules. In addition, we studied the electrochemical catalytic activity of the modified electrode towards a mixture of two protein bases (Adenine and Guanine). The modified gold nanodots ITO electrode was fabricated based on thermal evaporation of pure gold metal onto ITO surface through polystyrene monolayer. Then, a monolayer of 4–aminothiophenol was self–assembly immobilized onto the gold nanodots array/ITO electrode. This was followed by electrochemical polymerization process based on cyclic voltammetry technique. The electrochemical behavior of the adenine and guanine mixture at the modified electrode was investigated based on differential pulse voltammetry technique. The results indicated that the polymer nanostructures modified gold nanodots/ITO electrode exhibited an excellent electrocatalytic activity towards the oxidation of adenine and guanine with a detection limit of 500 and 250nM, respectively. Moreover, our finding demonstrated a linear relation between the concentration of both adenine and guanine and their oxidation current peaks (R=0.9953 and 0.9935, respectively). Finally, the modified electrode was successfully used to detect adenine and guanine in human serum sample. Therefore, we proposed that this biosensor could have high sensitivity for simultaneous determination of adenine and guanine in the related physiology process.

In vitroPlant Regeneration from Cotyledon and Hypocotyl Tissues of Tomato (Solanum lycopersicumL., cv. Solan Vajr)

In vitro plant regeneration was assessed in tomato (Solanum lycopersicum L. cv. Solan Vajr) using cotyledon and hypocotyl explants from two weeks old aseptically grown seedlings. Callus induction was achieved by culturing cotyledon and hypocotyl explants on Murashige and Skoog (MS) medium supplemented with different combinations and concentrations of BAP, IAA, NAA, TDZ and Adenine. Adventitious shoot buds were induced from calluses/explants by culturing on these media. Out of 54 different combinations of growth regulators (TDZ (alone), TDZ+Ad, TDZ+IAA, TDZ+NAA, TDZ+BAP), tried for cotyledon and hypocotyl explants separately, high frequency shoot regeneration from cotyledon (74.04%) and hypocotyl (79.61%) explants was obtained on MS medium supplemented with 2mg/l TDZ and 1.5mg/l TDZ+ 0.5μM IAA respectively. TDZ alone gave better results in comparison to TDZ in combination with other growth regulators in case of cotyledon explants while in case of hypocotyl explants TDZ along with IAA gave better results than TDZ (alone) and other combination of growth regulators. High percentage of root regeneration (95%) in in vitro developed shoots was obtained on MS medium supplemented with 0.2mg/l IBA in a short interval of 2 weeks. The regenerated plantlets after acclimatization were transferred to glass house conditions and both vegetative and floral characteristics were observed. An efficient and reproducible plant regeneration protocol has been standardized in tomato (Solanum lycopersicum cv. Solan Vajr). This regeneration system would be valuable in transgenic approaches for varietal improvement of tomato.

Association between Related Purine Metabolites and Diabetic Retinopathy in Type 2 Diabetic Patients

Aims. The purpose of the study was to investigate the differences of adenosine, adenine, inosine, xanthine, hypoxanthine, and uric acid concentrations in patients with type 2 diabetes mellitus and diabetic retinopathy and assess the relationship between purine metabolites and disease. Materials and Methods. The study group consisted of 114 subjects which were divided into three groups: control (n = 40), type 2 diabetes without retinopathy (n = 35), and type 2 diabetes with retinopathy (n = 39). Levels of metabolites were measured in plasma of all participants. Results. There is a significant increase of levels of adenosine (0.94 ± 0.17 mg/L versus 0.17 ± 0.01 mg/L, P < 0.001), inosine (0.297 ± 0.078 mg/L versus 0.086 ± 0.010 mg/L, P < 0.001), xanthine (1.01 ± 0.21 mg/L versus 0.54 ± 0.05 mg/L, P = 0.009), and uric acid (70.55 ± 3.97 mg/L versus 53.81 ± 2.36 mg/L, P < 0.001) with diabetic retinopathy compared to diabetes mellitus. The levels of adenine, hypoxanthine, and xanthine oxidase did not change. Uric acid, xanthine, inosine, and adenosine correlated positively with systolic blood pressure and urea nitrogen. Conclusions. The levels of adenosine, inosine, uric acid, and xanthine may be useful for monitoring the progression of diabetic retinopathy and evaluating the treatment.

Adenine deaminase is encoded by Tad1 and participates in copper accumulation in Trichoderma reesei

We cloned a novel Tad1 gene and demonstrated that this gene is closely involved in copper bioaccumulation in Trichoderma reesei. Tad1 gene encodes a 510 amino acids protein of the amidohydrolase superfamily which belongs to COG0402. We found that adenine was the most efficient substrate of Tad1 protein among the substrates used in this study. Gene function was also investigated by overexpression and RNA interference. Results showed that copper accumulation increased in mutant cells when Tad1 was overexpressed; by contrast, copper accumulation significantly decreased when Tad1 was inhibited. To investigate the function of Tad1 in copper bioaccumulation, we determined adenine, hypoxanthine, and xanthine concentrations by reversed phase HPLC. Tad1 overexpression induced a substantial production of xanthine, which functions in binding numerous copper ions and reducing copper concentration. We further compared the gene expression profile of AT01 with that of a wild-type T. reesei strain grown in a medium containing 1.0mM Cu2+ by performing DNA microarray. Several upregulated genes in the mutant were associated with adenine or copper metabolism.

Novel Tools to Analyze the Function of Salmonella Effectors Show That SvpB Ectopic Expression Induces Cell Cycle Arrest in Tumor Cells

In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ∆purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors.

Rapid in vitro multiplication and ex vitro establishment of Caribbean copper plant (Euphorbia cotinifolia L.): an important medicinal shrub

An efficient micropropagation protocol was developed for E. cotinifolia by utilizing mature nodal segments for axillary shoot proliferation. The nodal explants from a 2-year-old plant were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations (0.5, 2.5, 5.0, 7.5 and 10.0 μM) of 6-benzyladenine (BA), Kinetin and 2-isopentenyl adenine singly as well as in combination with α-naphthalene acetic acid (NAA) or Indole-3-butyric acid (IBA) (0.1, 0.5 and 1.0 μM). The highest regeneration frequency (92 %) with multiple shoots (13.0 ± 1.15) and shoot length (4.23 ± 0.14 cm) was achieved on MS medium supplemented with 5.0 μM BA and 0.1 μM NAA after 8 weeks of culture. Further experiments were performed to test the effects of medium type, medium strength, pH and subculture passages on shoot induction and proliferation. An enhancement in average number of shoots (16.6 ± 0.45) per explant was obtained after four subculture passages. Micro shoots exhibited in vitro rooting on half strength MS medium containing 2.5 μM Indole-3-butyric acid (IBA) after 4 weeks of culture. The in vitro raised healthy plantlets with well-developed roots and shoots were successfully acclimatized in plastic cups containing sterile soilrite for 8 weeks under culture room conditions (150 PPFD) prior to field transfer. Through the acclimatization period (0–56 days), photosynthetic pigments (Chlorophyll a, b and Carotenoid content) decreased during the initial 2 weeks followed by significant increase during the successive period (21–56 days) of acclimatization. At the same time, all the tested antioxidant enzymes (SOD, CAT, APX and GR) exhibited an increasing trend throughout the acclimatization period. The culture room acclimatized plantlets were successfully established in earthen pots containing garden soil in greenhouse with 70 % survival rate.

Arxula adeninivoransrecombinant adenine deaminase and its application in the production of food with low purine content

Construction of a transgenic Arxula adeninivorans strain that produces a high concentration of adenine deaminase and investigation into the application of the enzyme in the production of food with low purine content. The A. adeninivorans AADA gene, encoding adenine deaminase, was expressed in this yeast under the control of the strong inducible nitrite reductase promoter using the Xplor(®) 2 transformation/expression platform. The recombinant enzyme was biochemically characterized and was found to have a pH range of 5.5-7.5 and temperature range of 34-46 °C with medium thermostability. A beef broth was treated with the purified enzyme resulting in the concentration of adenine decreasing from 70.4 to 0.4 mg l(-1). It was shown that the production of adenine deaminase by A. adeninivorans can be increased and that the recombinant adenine deaminase can be used to lower the adenine content in the food. Adenine deaminase is one component of an enzymatic system that can reduce the production of uric acid from food constituents. This study gives details on the expression, characterization and application of the enzyme and thus provides evidence that supports the further development of the system.

A Novel Approach of Periodate Oxidation Coupled with HPLC-FLD for the Quantitative Determination of 3-Chloro-1,2-propanediol in Water and Vegetable Oil

A novel approach of periodate oxidation coupled with high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) for the quantitative determination of 3-chloro-1,2-propanediol (3-MCPD) has been established. The essence of this approach lies in the production of chloroacetaldehyde by the oxidization cleavage of 3-MCPD with sodium periodate and the HPLC analysis of chloroacetaldehyde monitored by an FLD detector after fluorescence derivatization with adenine. The experimental parameters relating to the efficiency of the derivative reaction such as concentration of adenine, chloroacetaldehyde reaction temperature, and time were studied. Under the optimized conditions, the proposed method can provide high sensitivity, good linearity (r(2) = 0.999), and repeatability (percent relative standard deviations between 2.57% and 3.44%), the limits of detection and quantification were 0.36 and 1.20 ng/mL, respectively, and the recoveries obtained for water samples were in the range 93.39-97.39%. This method has been successfully applied to the analysis of real water samples. Also this method has been successfully used for the analysis of vegetable oil samples after pretreatment with liquid-liquid extraction; the recoveries obtained by a spiking experiment with soybean oil ranged from 96.27% to 102.42%. In comparison with gas chromatography or gas chromatography-mass spectrometry, the proposed method can provide the advantages of simple instrumental requirement, easy operation, low cost, and high efficiency, thus making this approach another good choice for the sensitive determination of 3-MCPD.

The purine nucleotides guanine, adenine and inosine are a dietary requirement for optimal growth of black tiger prawn, P. monodon

Prawns have a dietary requirement for nucleotides for optimum growth. Commercial diets and many natural feed ingredients, including fishmeal are high in nucleotides, with guanine and its derivatives contributing the highest proportion of total nucleotide. The aim of this study was to test the role of guanine alone and in combination with other purified nucleotides on growth, survival rate and non-specific immunity of prawns using a supplemented semi-purified diet. Semi-purified diets as basal (or control) and basal diets supplemented with 0.4% GMP, 0.5% GMP and with combinations of 0.4% GMP with 0.1% of each of AMP, CMP, IMP or UMP were used to feed the prawns (initial mean weight of 3.83±0.01g) for 53days. Two positive control diets, one comprising the semi-purified diet supplemented with a commercial nucleotide mixture, Optimun at 2.27% (0.5% total nucleotide) and a commercial diet, Lucky Star, were also included. Supplementation levels were chosen based on the optimal total nucleotide content determined in previous trials with the semi-purified diet. Growth rates of prawn (DGC, %/day) were significantly higher in groups of prawn fed diets supplemented with 0.5% GMP, GMP+AMP, GMP+IMP than prawns fed the basal, 0.4% GMP, and GMP+UMP (p≤0.030). THC were highest in groups of prawns fed diets containing GMP+AMP, GMP+IMP, GMP+CMP and the basal diet supplemented with Optimun (32×106–33×106cells/mL) and were significantly higher than THC in groups of prawns fed basal diet and diet supplemented with 0.4% GMP alone (~26.5×106cells/mL) (p≤0.038). On day 52, concentrations of guanine, adenine, total purine and total nucleotide in prawn diets were highly positively correlated with weight of prawns (p≤0.013), whilst THC was significantly correlated with guanine, total purine and total nucleotide content (p≤0.023). Survival rates of prawns were very high (between 92 and 100%) and did not differ significantly among diet treatments (p=0.449). Purine nucleotides, especially guanine, appear to be critical for optimal growth of black tiger prawn, Penaeus monodon.

A Biotechnological Approach for the Production of Red Gerbera (Gerbera Jamesonii Bolus)

An in vitro propagation of a red Gerbera (Gerbera jamesonii) variety was achieved by culturing flower bud, leaf segments and flower stalk segments of 80 days old field grown plants on Murashige and Skoog (MS) medium supplemented with different concentration (1.0-6.0 mg/l) of 6-benzyl adenine (BA) in combination with single concentration (1.0 mg/l) of α-naphthalene acetic acid (NAA). Lower concentration of BA (1.0 and 2.0 mg/l) with NAA induced the explants to form callus. On the other hand when the explants were cultured in higher concentration (5.0 mg/l) of BA produced shoots and 5.0 mg/l BA with 1.0 mg/l NAA was found to be the best for shoot proliferation of the three explants optimum response was obtained from flower buds. Further multiplication of shoots occurred upon transfer of shoot clumps to BA containing MS medium. Regenerated shoots were rooted in MS medium with indole-3-acetic acid (IAA) or indole-3-buteric acid (IBA) and maximum frequency (81%) of rooting with highest number (4) of roots per shoot was achieved in MS medium fortified with 0.3 mg/l IBA. The rooted shoots were acclimatized and successfully established in soil under natural environment with maximum 84% survivability.

Characterizing the intracellular distribution of metabolites in intact Chlamydia-infected cells by Raman and two-photon microscopy

Chlamydia species are obligate intracellular pathogens that proliferate only within infected cells. Currently, there are no known techniques or systems that can probe the spatial distribution of metabolites of interest within intact Chlamydia-infected cells. Here we investigate the ability of Raman microscopy to probe the chemical composition of different compartments (nucleus, inclusion, and cytoplasm) of Chlamydia trachomatis-infected epithelial cells. The overall intensity of the Raman spectrum is greatest in the inclusions and lowest in the cytoplasm in fixed cells. Difference spectra generated by normalizing to the intensity of the strong 1004 cm−1 phenylalanine line show distinct differences among the three compartments. Most notably, the concentrations of adenine are greater in both the inclusions and the nucleus than in the cytoplasm, as seen by Raman microscopy. The source of the adenine was explored through a complementary approach, using two-photon microscopy imaging. Autofluorescence measurements of living, infected cells show that the adenine-containing molecules, NAD(P)H and FAD, are present mainly in the cytoplasm, suggesting that these molecules are not the source of the additional adenine signal in the nucleus and inclusions. Experiments of infected cells stained with a DNA-binding dye, Hoechst 33258, reveal that most of the DNA is present in the nucleus and the inclusions, suggesting that DNA/RNA is the main source of the additional Raman adenine signal in the nucleus and inclusions. Thus, Raman and two-photon microscopy are among the few non-invasive methods available to investigate cells infected with Chlamydia and, together, should also be useful for studying infection by other intracellular pathogens that survive within intracellular vacuoles.

Study of Shoot Multiplication of Strawberry (Fragaria ananassa)

Effects of different hormonal concentration on multiple shoot formation of RABI Strawberry-3 were studied. Where the explants were runner tips that cultured on MS basal medium supplemented with 6-Benzyl Adenine and Kinetin. The maximum percentage 80% of shoot was obtained from Benzyl Adenine concentrations of 0.5 mg/l and 1.0 mg/l whereas Kinetin concentrations were 1.5 mg/l and 2.0 mg/l separately. More promising result was found by combining two impressive concentrations of each hormone. When MS basal media was supplemented with Kinetin 2.0mg/l + Benzyl Adenin A 0.5 mg/l, Kinetin 1.5 mg/l + Benzyl Adenine 0.5 mg/l and Kinetin 1.5 mg/l + Benzyl Adenine 1.0 mg/l respectively then 100% shoots were obtained. DOI: http://dx.doi.org/10.3329/ijarit.v1i1-2.13936 Int. J. Agril. Res. Innov. &amp; Tech. 1 (1&amp;2): 69-72, December, 2011

Association of poly(N-isopropylacrylamide) containing nucleobase multiple hydrogen bonding of adenine for DNA recognition

In this study we used the poly(N-isopropylacrylamide) (PNIPAAm) as a medium to generate PNIPAAm–adenine supramolecular complexes. A nucleobase-like hydrogen bonding (NLHB) between PNIPAAm and adenine was found that changed the morphology, crystalline structure, and temperature responsiveness of PNIPAAm microgels relatively to the adenine concentrations. With increasing the adenine concentration, the PNIPAAm–adenine supramolecular complexes gradually altered their morphologies from microgel particles to thin film structures and suppressed the thermodynamical coil-to-globule transition of PNIPAAm because of the NLHB existed between the PNIPAAm amide and ester groups and the adenine amide groups (CO⋯HN and NH⋯NR), verified by FTIR spectral analysis. NLHB was also diverse and extensive upon increasing the temperature; therefore, the thermoresponsive behavior of the complexes was altered with the NLBH intensity, evaluated by the inter-association equilibrium constant (Ka) above and below their LCST. Therefore, PNIPAAm can be as a medium to recognize adenine in various concentrations, which could potentially be applied in DNA recognition.

Electrochemical characterization of redox polymer modified electrode developed for monitoring of adenine

Electrochemical characterization of redox polymer for monitoring of adenine was described in this study using poly(vinylferrocenium) (PVF+) modified platinum (Pt) electrode. Scanning electron microscope (SEM) was used for the surface characterization. The electrochemical behaviors of polymer modified and adenine immobilized polymer modified electrodes were investigated by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In order to obtain more sensitive and improved electrochemical signals, analytical parameters such as the effects of polymeric film thickness, immobilization time of adenine, pH and adenine concentration were examined on the response of the polymer modified electrode. Alternating current (AC) impedance spectroscopy was used for the characterization of polymer modified and adenine immobilized polymer modified electrodes. The effect of possible interferents on the response of the electrode was examined.

A Study of the Effect of Isoproterenol on Red Blood Cell Concentrations of Adenine Nucleotides in a Freely Moving Rat Model In Vivo*

Previous studies have shown that red blood cell (RBC) concentrations of adenine 5’-triphosphate (ATP) may be a key factor for post exercise effects responsible for cardiovascular protection. To test this concept further, we investigated the effect of isoproterenol on ATP metabolism in RBC using a freely moving rat model in vivo. Sprague Dawley rats were given either isoproterenol (30 mg/kg) or saline by subcutaneous (sc) injection. Blood samples were collected sequentially for up to 6 hours for measurement of adenine nucleotides in the RBC. Hemodynamic recordings were collected throughout the experiment. We have found isoproterenol induced 50% mortality under the experimental condition. It decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP) immediately after the injection by -64 ± 22 and -64 ± 20 mmHg in less than 15 min, and increased HR steadily by +158 ± 59 bpm at the end of the experiment. Isoproterenol also increased RBC concentrations of adenine 5’-monophosphate (AMP) from 0.04 ± 0.01 to 0.28 ± 0.23 mM (+500%). The rats died had much greater breakdown of ATP to adenosine 5’-monophosphate (AMP) in the RBC than those surviving from the injury (p<0.05 for all the comparison).

Simultaneous determination of guanine, adenine and thymine using a modified carbon paste electrode by TiO2 nanoparticles-magnesium(II) doped natrolite zeolite

A novel, simple and reliable electrochemical method for simultaneous determination and direct electro-oxidation behaviors of guanine (G), adenine (A) and thymine (T) was developed at a TiO2 nanoparticles-magnesium doped zeolite Y modified carbon paste electrode (TiO2NPs-MgY/ZMCPE). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were used to examine the structure of the TiO2NPs-MgY/ZMCPE. The measurements were carried out using cyclic voltammetry in phosphate buffer solution with pH 7.2. This modified electrode exhibits potent and persistent electro-oxidation behavior followed by well-separated oxidation peaks toward G, A and T with increasing the oxidation current. The electrochemical behaviors of guanine, adenine and thymine on the modified electrode were carefully studied by cyclic voltammetry and the electrochemical parameters such as the area of the electrode (A), the electron transfer number (n), the electron transfer coefficient (α), the electrode reaction standard rate constant (ks), and the surface coverage (ГT) were calculated. Differential pulse voltammetry (DPV) was proposed for simultaneous determination of three DNA bases. Under the selected conditions the oxidation peak currents were proportional to guanine, adenine and thymine concentrations in the range from 0.1 to 100μM, 0.1 to 100μM and 8 to 1000μM respectively with the detection limit as 0.013, 0.02 and 0.878μM (3σ) and relative standard deviation (RSD%) 5.25%, 6.5% and 8.63% (n=10 for guanine, adenine and thymine respectively). The proposed method showed good selectivity to the G, A and T detection without the interferences of coexisting substances.